Knife for peeling off stickers and the like

ABSTRACT

A knife has a flat reverse face and a beveled cutting face on the opposite side with a bevel dihedral angle of approximately 15* and a truncated extreme cutting edge in the form of a blunt leading edge, narrow regions respectively of the beveled cutting face and the reverse face immediately adjacent to and extending along the leading edge being further beveled with minute bevel angles each of approximately 2.5* relative to the beveled cutting face and the reverse face. When a knife of this shape is advanced with the leading edge in front into the thin adhesive layer of a sticker adhering to a fragile paper surface, it shaves the adhesive layer very close to and parallel to the paper surface without damaging it.

United States Patent [1 1 3,818,592 Himeno June 25, 1974 154] KNIFE FORPEELING OFF STICKERS AND FOREIGN PATENTS OR APPLICATIONS THE LIKE660,891 11/1951 Great Britain 30/357 [75] Inventor: Shohachi Himeno,Tokyo-to, Japan 1,016,199 10/1964 Great Britain 30/346 7 C K h K T 3]Asslgneg 32?: abus [kl alsha Okyo to Primary Examiner-Al Lawrence SmithAssistant Examiner.l. C. Peters [22] Filed: May 7, 1973 Attorney, Agent,or Firm-Eric l-l. Waters [2]] Appl. No.: 358,161

[57] ABSTRACT 30 Forei n A licafi n Prior-t Data A knife has a flatreverse face and a beveled cutting 1 M 20 o 47 50025 face on theopposite side with a bevel dihedral angle l 972 Japan 47-58904 ofapproximately 15 and a truncated extreme cutting 3y apan edge in theform of a blunt leading edge, narrow regions respectively of the beveledcutting face and the 8 30/151 30/ 23 1 433; reverse face immediatelyadjacent to and extending 58 i IIIIIIII 5 357 o g the leading edge beingfurther beveled with min- 1 0 care ll 51 5/36 ute bevel angles each ofapproximately 25 relative to the beveled cutting face and the reverseface. When a knife of this shape is advanced with the leading edge [56]References cued in front into the thin adhesive layer of a stickeradher- UMTED STATES PATENTS ing to a fragile paper surface, it shavesthe adhesive 2,484,692 10/1949 Deluce 30/353 X layer very close to andparallel to the paper surface 2,901.823 9/1959 Widen 1 30/151 ithoutdamaging it 3,292,478 12/1966 Falk .4 30/357 X 0 3,492.903 2/1970 Malm30/346 x 4 Claims, 7 a ng gures U 'J 1 2 loo Q g @717 l i PATENTEDJUNZS1974 SHEET 1 [1F 2 KNIFE FOR PEELING OFF STICKERS AND THE LIKEBACKGROUND This invention relates generally to cutlery-like tools andmore particularly to a knife for peeling or exfoliating sticking piecessuch as labels seals, tapes, and the like off paper sheet surfaces,surfaces of paper containers, and the like fragile surfaces.

When such a sticking piece (hereinafter referred to as a sticker)adhering to a paper sheet surface or surface of a paper container ispeeled or stripped off by conventional procedure, the underlying papersurface tends to be stripped off by the adhesive on the sticker. Thisresults from forceful pulling off of the adhesive adhering to the papersurface from that surface.

In the case where an ordinary sticker is stuck onto a paper surface, thethickness of the adhesive layer interposed therebetween is of the orderof I/ 1,000 mm. If it were possible to cut or split this adhesive layerparallelly to the paper surface and, moreover, as close as possible tothe paper surface, it would be possible to peel off the sticker withoutdamaging the paper surface.

However, with a knife of the types in general use with sharp cuttingedges, it is extremely difficult to make such a cut or split in a steadymanner as a spacing of less than I/ l ,000 mm. is maintained between theknife cutting edge and the paper surface, the likely result being aninadvertent cut into the paper surface.

SUMMARY In view of the above described difficulties, it is an object ofthis invention to provide a knife for peeling off stickers capable ofcutting through the above mentioned adhesive layer parallelly and asclosely as possible to the paper surface.

According to this invention in one aspect thereof, there is provided aknife for peeling off stickers and the like characterised in that it hasa knife blade made of va thin, elastic strip beveled to form a beveledcutting face on only one side along at least one lateral edge thereof,the opposite reverse face being substantially flat and forming an acutebevel or dihedral angle with the beveled cutting face, the resultingdihedral intersection being truncated to form a blunt leading edgesubstantially perpendicular to the reverse face, very narrow regionsrespectively of the beveled cutting and reverse faces immediatelyadjacent and extending along the leading edge being further beveled withminute bevel angles.

According to this invention in a further aspect I thereof, there isprovided a knife of the above stated character further characterised bythe combination thereof with a handle secured to the tang of the bladeand a sheath having a cavity with an entrance to accommodate the bladeand having strips of a wiping material secured to the inner wall surfaceof the cavity from the entrance thereof inward and serving to wipe theblade as his inserted into and extracted from the cavity.

The nature, principle, and utility of this invention will be moreclearly apparent from the following detailed description with respect topreferred embodiments of the invention when read in conjunction with theac- 2 companying drawings, in which like parts are designated by likereference numerals.

DRAWINGS In the drawings:

FIG. 1 is a plan view showing one example of a knife blade according tothis invention;

FIG. 2 is an enlarged, fragmentary cross section of the edge part of theknife blade;

FIG. 3 is a fragmentary cross section indicating a state of use of theknife blade;

FIG. 4 is a plan view showing another example of a knife blade accordingto this invention having two beveled cutting faces on the same sidealong respective lateral edges;

FIG. 5 is a plan view showing the exterior of a knife according to theinvention having a blade in combination with a handle and a sheath;

FIG. 6 is a longitudinal section of the combination shown in FIG. 5; and

FIG. 7 is a cross section of the combination shown in FIG. 5.

DETAILED DESCRIPTION Referring first to FIGS. 1, 2, and 3, the knifeblade body 1 shown therein is formed from a highly elastic material suchas, for example, a carbon tool steel of a carbon content of from l.l0 to1.30 percent, maximum silicon content of 0.35 percent, and maximummanganese content of 0.50. The blade width is of the order of 9 mm. atthe tip la, 18 mm. at the base or heel lb, and 12 mm. at the tang 1c.The overall length is of the order of 200 mm. including a tang 1c lengthof the order of mm.

One lateral edge of the blade body 1 is beveled to form a beveledcutting face 2, which is inclined with an dihedral angle of the order ofl5 relative to the plane of the flat reverse face 3 and has a width ofthe order of 2 mm.

A cutting or leading edge 4 constituting the extreme outer edge of theblade is in the form of a flat, cut-off or truncated surfaceperpendicular to the plane of the reverse face 3. This leading edge 4 isformed by cutting off approximately 1 mm. of the sharp edge of a cuttingedge formed by the intersection of the plane of the reverse face 3 andthe inclined plane of the beveled cutting face 2. The width of thisleading edge 4 is of the order of from 0.02 to 0.03 mm.

The extreme edge regions of the beveled face 2 and the reverse face 3adjacent to the leading edge 4 are further beveled to form narrowbeveled peeling edges 5 and 6, respectively, each of a width ofapproximately 0.03 mm. These beveled peeling edges 5 and 6 are inclinedwith an inclination angle of the order of 2.5 degrees relative to thebeveled cutting face 2 and the reverse face 3, respectively.

The peeling edges 5 and 6 are preferably satin finished or hairlinefinished in the direction perpendicular to the leading edge 4 thereby toprevent sticking of adhesive thereto.

The manner in which the knife blade 1 of the above described naturepeels a sticker 7 with an adhesive 9 from a piece of paper 8 isindicated in FIG. 3, in which the relative dimensions of the parts ofthe materials and the knife blade have been selected for clarity inillustration and differ from those in an actual case.

For this peeling operation, one edge of the sticker 7 adhering to thepaper 8 is pulled slightly apart from the paper to form a minute gaptherebetween. The leading edge 4 is then inserted into this gap, and theblade 1 with the edge 4 leading the way is pressed toward the peelingdirection as it is caused to undergo minute back-and-forth movements inits longitudinal direction.

During this peeling action, the reverse face 3 of the blade is held flatagainst the paper surface. As a result, the blade 1 is bent into acurved figure with the tang 1c inclined upward toward its rear end.

As the blade 1 advances in its peeling action with the leading edge 4 inthe van and the reverse face 3 held flat against the surface of thepaper 8, the sticker 7 is induced to follow the blade along the beveledpeeling edge 5, while the leading edge 4 at its lower edge splits orseparates the adhesive layer 9 at a position close to the surface of thepaper 8. It has been found that, as a result of this splitting action,the adhesive layer remaining on the paper side is of a thickness of theorder of from 0.0001 to 0.0002 mm. and, therefore, is almost invisibleto the naked eye.

In a modification of the example of the knife according to the inventionas described above, beveled cutting faces 2, 2 are formed along bothlateral edges of the blade 1 on the same side thereof as shown in FIG.4. Each of these beveled faces 2, 2 and the related parts, that is, theleading edge 4 and the beveled peeling edges and 6, are the same indimension, and shape as those of the preceding example, and the reverseface 3 is also flat except for the beveled peeling edges 6, 6 at itsextreme lateral edge parts. In this example, also, the beveled peelingedges 5 and 6 are satin finished or hairline finished to prevent orgreat reduce sticking of adhesive at the time of peeling operation.

The knife blade of this invention, whether it is single edged as shownin HO. 1 or whether it is double edged as shown in FIG. 4, is renderedconvenient for practical use by the provision of a handle such as ahandle 10 comprising a combination of two halves 10a and 10b securedonto the opposite sides of the tang 1c of the knife blade.

In addition, a scabbard or sheath 11 is provided for insertion thereintoof the exposed part of the knife blade 1 from the tip In to the heel 1b.This sheath 11 is formed from two halves 11a and 11b secured to getherwith a cavity therebetween for accommodating the blade. Beginning at theentrance of this sheath 11 and extending inward for approximately 40percent of the length of the cavity, there are provided strips 12, 12 ofa soft material processed with a silicon resin such as, for example,so-called silicone cloth, bonded respectively to the inner wall surfacesof the sheath halves 11a and 1 lb.

When the knife is not being used, the blade 1 is normally sheathed inthe sheath 11. When the knife is to be used, the blade 1 is drawn out ofthe sheath 1!, whereupon the blade 1 is wiped clean by the siliconecloth strips 12, 12, whereby the adhesive such as that in the adhesivelayer 9 is prevented from adhering to the blade 1 when it advancesthrough the adhesive layer.

Thus, the knife according to this invention is capable of peelingstickers and the like sticking to paper and other fragile surfaces offthese surfaces very easily and in a clean manner without damaging theunderlying surfaces.

I claim:

1. A knife for peeling off stickers and the like, comprising a knifeblade body (1) made of a thin strip of an elastic material and having atang (1c) and a cutting blade (la, lb) beveled to form a beveled cuttingface (2) on only one side along at least one lateral edge thereof, theopposite reverse face (3) being substantially flat and forming an acutedihedral angle with the beveled cutting face, the resulting dihedralintersection being truncated to form a blunt leading edge (4)substantially perpendicular to the reverse face, very narrow regionsrespectively of the beveled cutting face and the reverse faceimmediately adjacent to and extending along the leading edge beingfurther beveled with minute bevel angles to form respective beveledpeeling edges (5) (6).

2. A knife as claimed in claim 1 in which: said dihedral angle is of theorder of 15; each of said minute bevel angles respectively relative tothe beveled cutting face (2) and the reverse face (3) is of the order of2.5 degrees; the beveled cutting face (2) has a width of the order of 2mm. for an average width of the cutting blade of the order of 13.5 mm.;each of said beveled peeling edges (5) (6) has a width of the order of0.03; and the leading edge (4) has a width of the order of from 0.02 to0.03 mm.

3. A knife as claimed in claim 2 in which said elastic material is asteel of a carbon content of the order of l .20'percent.

4. A knife as claimed in claim 1 which further comprises, in combinationtherewith, a handle 10 secured to the tang 1c and a sheath 11 having acavity with an entrance to accommodate the cutting blade and havingstrips of a silicone cloth secured to the inner wall surface of thecavity from the entrance thereof inward and serving to wipe the cuttingblade as it is inserted into and drawn out from the cavity.

1. A knife for peeling off stickers and the like, comprising a knifeblade body (1) made of a thin strip of an elastic material and having atang (1c) and a cutting blade (1a, 1b) beveled to form a beveled cuttingface (2) on only one side along at least one lateral edge thereof, theopposite reverse face (3) being substantially flat and forming an acutedihedral angle with the beveled cutting face, the resulting dihedralintersection being truncated to form a blunt leading edge (4)substantially perpendicular to the reverse face, very narrow regionsrespectively of the beveled cutting face and the reverse faceimmediately adjacent to and extending along the leading edge beingfurther beveled with minute bevel angles to form respective beveledpeeling edges (5) (6).
 2. A knife as claimed in claim 1 in which: saiddihedral angle is of the order of 15*; each of said miNute bevel anglesrespectively relative to the beveled cutting face (2) and the reverseface (3) is of the order of 2.5 degrees; the beveled cutting face (2)has a width of the order of 2 mm. for an average width of the cuttingblade of the order of 13.5 mm.; each of said beveled peeling edges (5)(6) has a width of the order of 0.03; and the leading edge (4) has awidth of the order of from 0.02 to 0.03 mm.
 3. A knife as claimed inclaim 2 in which said elastic material is a steel of a carbon content ofthe order of 1.20 percent.
 4. A knife as claimed in claim 1 whichfurther comprises, in combination therewith, a handle 10 secured to thetang 1c and a sheath 11 having a cavity with an entrance to accommodatethe cutting blade and having strips of a silicone cloth secured to theinner wall surface of the cavity from the entrance thereof inward andserving to wipe the cutting blade as it is inserted into and drawn outfrom the cavity.